The invention relates to a resonator and more particularly to a variable tuned telescoping resonator for control of engine induction noise in a vehicle wherein the connector length and volume of the resonator are varied simultaneously.
In an internal combustion engine for a vehicle, it is desirable to design an air induction system in which sound energy generation is minimized. Sound energy is generated as fresh air is drawn into the engine. Vibration is caused by the intake air in the air feed line which creates undesirable intake noise. Resonators of various types such as a Helmholtz type, for example, have been employed to reduce engine intake noise. Such resonators typically include a single, fixed volume chamber for dissipating the intake noise. Additionally, multiple resonators are frequently required to attenuate several noise peaks of different frequencies.
Desired noise level targets have been developed for a vehicle engine induction system. When engine order related inlet orifice noise targets are specified to be within narrow limits as a function of engine speed, the target line often cannot be met with a conventional multi-resonator system. The typical reason is that conventional resonator systems provide an attenuation profile that does not match the profile of the noise and yields unwanted accompanying side band amplification. This is particularly true for a wide band noise peak. The result is that when a peak value is reduced to the noise level target line at a given engine speed, the amplitudes of adjacent speeds are higher than the target line. Thus, the resonators are effective at attenuating noise at certain engine speeds, but ineffective at attenuating the noise at other engine speeds.
It would be desirable to produce a resonator which is variable tuned to militate against the emission of sound energy caused by the intake air at a wide range of engine speeds.
Consistent and consonant with the present invention, a variable tuned telescoping resonator which militates against the emission of sound energy caused by the intake air at a wide range of engine speeds, has surprisingly been discovered.
The variable tuned resonator system comprises:
an inner telescoping section adapted to provide fluid communication with a duct, the inner telescoping section defining a resonator connector length; and
an outer telescoping section surrounding the inner telescoping section to define a chamber therebetween, the inner telescoping section and the outer telescoping section being selectively extensible and collapsible to thereby change at least one of a volume of the chamber and the resonator connector length;
wherein changing the at least one of the volume of the chamber and the resonator connector length facilitates attenuation of a desired frequency of sound entering the resonator.